Pattern events

src/core/base.js

@@ -61,6 +61,9 @@ Base.prototype = {
     on(eventName, eventCallback) {
         this.$el.on(`${eventName}.${this.name}.patterns`, eventCallback);
     },
+    one(eventName, eventCallback) {
+        this.$el.one(`${eventName}.${this.name}.patterns`, eventCallback);
+    },
     emit(eventName, args) {
         // args should be a list
         if (args === undefined) {

src/core/base.test.js

@@ -135,13 +135,33 @@ describe("pat-base: The Base class for patterns", function () {
         new Tmp3($("<div>"), { option: "value" });
     });
 
-    it("has on/emit helpers to prefix events", function () {
+    it("has on/emit helpers to prefix events", function (done) {
         var Tmp = Base.extend({
             name: "tmp",
             trigger: ".pat-tmp",
             init: function () {
                 this.on("something", function (e, arg1) {
                     expect(arg1).toEqual("yaay!");
+                    done();
+                });
+                this.emit("somethingelse", ["yaay!"]);
+            },
+        });
+        new Tmp(
+            $("<div/>").on("somethingelse.tmp.patterns", function (e, arg1) {
+                $(this).trigger("something.tmp.patterns", [arg1]);
+            })
+        );
+    });
+
+    it("has ``one`` helper to prefix events", function (done) {
+        var Tmp = Base.extend({
+            name: "tmp",
+            trigger: ".pat-tmp",
+            init: function () {
+                this.one("something", function (e, arg1) {
+                    expect(arg1).toEqual("yaay!");
+                    done();
                 });
                 this.emit("somethingelse", ["yaay!"]);
             },

src/core/events.js

@@ -58,6 +58,41 @@ const remove_event_listener = (el, id) => {
     }
 };
 
+/**
+ * Await an event to be thrown.
+ *
+ * Usage:
+ *     await events.await_event(button, "click");
+ *
+ * @param {DOM Node} el - The element to listen on.
+ * @param {String} event_name - The event name to listen for.
+ *
+ * @returns {Promise} - Returns a Promise which can be used for ``await`` and which will be resolved when the event is throwm.
+ *
+ */
+const await_event = (el, event_name) => {
+    // See: https://stackoverflow.com/a/44746691/1337474
+    return new Promise((resolve) =>
+        el.addEventListener(event_name, resolve, { once: true })
+    );
+};
+
+/**
+ * Await pattern init.
+ *
+ * Usage:
+ *     await events.await_pattern_init(PATTERN);
+ *
+ * @param {Pattern instance} pattern - The pattern instance.
+ *
+ * @returns {Promise} - Returns a Promise which can be used for ``await`` and which will be resolved when the event is throwm.
+ *
+ */
+const await_pattern_init = (pattern) => {
+    // See: https://stackoverflow.com/a/44746691/1337474
+    return new Promise((resolve) => pattern.one("init", resolve));
+};
+
 /**
  * Event factories
  */
@@ -100,6 +135,8 @@ const submit_event = () => {
 export default {
     add_event_listener: add_event_listener,
     remove_event_listener: remove_event_listener,
+    await_event: await_event,
+    await_pattern_init: await_pattern_init,
     click_event: click_event,
     change_event: change_event,
     input_event: input_event,

src/core/events.test.js

@@ -1,3 +1,4 @@
+import Base from "./base";
 import events from "./events";
 import utils from "./utils";
 
@@ -47,6 +48,35 @@ describe("core.events tests", () => {
 
             done();
         });
+
+        it("Awaits an event to happen", async () => {
+            const el = document.createElement("div");
+
+            window.setTimeout(() => {
+                el.dispatchEvent(new Event("init"));
+            }, 1);
+
+            await events.await_event(el, "init");
+
+            // If test reaches this expect statement, all is fine.
+            expect(true).toBe(true);
+        });
+
+        it("Awaits a pattern to be initialized", async () => {
+            const pat = Base.extend({
+                name: "tmp",
+                trigger: ".pat-tmp",
+                init: function () {},
+            });
+
+            const el = document.createElement("div");
+            const instance = new pat(el);
+
+            await events.await_pattern_init(instance);
+
+            // If test reaches this expect statement, all is fine.
+            expect(true).toBe(true);
+        });
     });
 
     describe("2 - event factories", () => {